1. Field of the Invention
The invention relates to a sight-line end estimation device that estimates a driver's sight-line end.
2. Description of the Related Art
Sight-line end estimation devices that estimate at what object a driver is directing his/her sight line in order to assist the driver have been developed. A sight-line end estimation device of a vehicle, for example, detects the driver's sight-line direction, and detects the relative direction of each of the target objects (vehicles, persons, etc.) that exist around the host vehicle relative to the host vehicle, and determines at which one of the target objects the driver is directing his/her sight line by comparing the direction of the sight-line with each of the relative directions of the target objects, and determines whether the driver is aware of a risk or danger (see (Japanese Patent Application Publication No. 2005-134971 (JP-A-2005-134971)).
In the above-described sight-line end estimation device, the position of the driver's eyes and the position of the detection means that has detected the relative directions of the target objects are different from each other, so that simple comparison between the sight-line direction and the relative directions cannot provide accurate estimation of a target object at which the driver is actually directing his/her sight line. FIG. 10 shows an example of a relationship between the sight-line direction α of a driver D (the angle thereof with respect to the longitudinal direction of the vehicle) and the relative directions γ, β of target objects Oa, Ob detected from a sight field image provided by a sight field video picture camera C (the angles thereof with respect to the longitudinal direction of the vehicle). In this example, the target object Oa and the target object Ob both exist in the sight-line direction α of the driver D. However, since the position of the eyes of the driver D and the position of the sight field video picture camera C are different from each other, the relative direction γ of the target object Oa and the relative direction β of the target object Ob detected from the sight field image provided by the sight field video picture camera C are different from each other, and are also different from the sight-line direction α of the driver D. Therefore, when the sight-line direction α is compared with the relative directions γ, β, it may not be able to be determined that the driver is looking at the target object Oa.